---
title: "在history页面新增一个弹窗，显示：下一期尾数与前一期尾数相同的概率、下一期首位与前一期首位相同的概率"
mode: quick
status: complete
date: 2026-05-02
---

## Summary

Completed quick task: Added a "尾首概率" (Tail-Head Probability) dialog to the history page.

### Changes
- `application/admin/model/History.php` — Added `getTailHeadProbability()` method that analyzes consecutive period transitions of the special code (num7), calculating the probability of tail (ones digit) and head (tens digit) remaining the same
- `application/admin/controller/History.php` — Added `tailHeadProb` endpoint + added to `$noNeedRight`
- `application/admin/view/history/index.html` — Added toolbar button with `btn-tailheadprob` class
- `public/assets/js/backend/history.js` — Added click handler + `showTailHeadProbabilityDialog()` with period selector (30/50/100/200)

### Implementation details
- Tail = num % 10 (个位), Head = floor(num / 10) (十位)
- Only counts valid transitions (both numbers in 1-49 range)
- Displays probability as percentage with period count and transition count